Thermoregulator is generally used in the cooling system of an engine. The thermoregulator can be opened or closed automatically according to the temperature of a cooling liquid to change the flowing path of the cooling liquid, and thus to regulate the temperature of the engine.
The working principle of the conventional thermoregulator is taking advantage of the characteristic of expanding with heat and contracting with cold, of some materials, such as paraffin. When the temperature of cooling liquid is low, the thermoregulator is closed. The thermoregulator will be opened due to the expanding of paraffin with heat when the temperature of cooling liquid reaches a predetermined temperature. However, when the thermoregulator is opened, the variation of liquid flow rate cannot be precisely controlled.
Thus, there is a need for a thermoregulator which allows precise control of variation of liquid flow rate, and hence rate of energy transfer, even when the temperature is high enough for the thermoregulator to open.